1. Field of the Invention
The present invention relates to an instant film pack. More particularly, the present invention relates to an instant film pack suitable for use with an optical printer for printing an image on an instant photo film.
2. Description Related to the Prior Art
Various types of instant film packs are commercially available, each of which has a case in a quadrilateral shape for containing instant photo films of a mono-sheet type. This is a self-processing photo film unit, of which a photosensitive layer is exposed first. Developing solution contained therein is spread for processing an exposed image, to create the image on the instant photo film. To use the instant photo film, an instant camera is mainly loaded with the instant film pack.
The instant photo films must be kept shielded from light. To prevent unwanted exposure before loading into the instant camera, a light-tight case containing the instant photo films is set into the instant camera. U.S. Pat. No. 6,195,508 (corresponding to JP-A 2000-089351) discloses the use of the case for the instant photo films. The case includes an exposure opening, an exit slot, and a claw path opening. The exposure opening causes a photosensitive surface of the instant photo film to appear. The exit slot is formed for ejecting the instant photo film being exposed. The claw path opening receives entry of an advancing claw mechanism well-known in the art for advancing a first one of the instant photo films in the case toward the exit slot.
In the case, the exposure opening, the exit slot and the claw path opening are closed in various elements. For the exit slot, a light shielding flap of a sheet shape has light-tightness and flexibility, and is attached to an outer side of the exit slot. For the exposure opening, a light shielding cover is used, and sandwiched between the inside of the exposure opening and a first one of the instant photo films. The claw path opening is closed by a light shielding sheet having light-tightness and flexibility. The light shielding sheet has one end attached to the light shielding cover. The light shielding cover is ejected by the advancing claw mechanism from the case when the instant camera becomes loaded with the instant film pack completely. At the same time, the light shielding flap is pushed to open the exit slot. The light shielding sheet at the claw path opening is ejected together from the case.
The instant film pack for use with the conventional camera has a problem in that the instant photo film is likely to thrust and exit accidentally from the exit slot if shock or vibration is given to the instant film pack, for example the instant film pack is dropped on to a floor. To prevent such a problem, a thrust preventing flap is suggested, and attached to inside of the exit slot to close one portion of the exit slot. According to this, the thrust preventing flap is attached and supported on the light shielding cover, which will be ejected and removed from the inside of the case together with the thrust preventing flap.
Furthermore, an optical printer is known in the art to record an image by use of the instant photo film, for example, JP-A 2001-356423 and U.S. Pat. No. 6,734,948 (corresponding to JP-A 2002-221778).
The optical printer according to JP-A 2001-356423 and U.S. Pat. No. 6,734,948 (corresponding to JP-A 2002-221778) is a line printing type in which an image is exposed one line after another with a line-shaped exposure head in feeding the instant photo film. Therefore, the exposure opening at a size of appearance of a large area of the photosensitive side is unnecessary for a case of the instant film pack for use with the optical printer. In JP-A 2001-356423, the exposure opening in the instant film pack has a slot form with a small width. Furthermore, U.S. Pat. No. 6,734,948 (corresponding to JP-A 2002-221778) discloses the optical printer in which a first step is to advance the instant photo film from the case, and a second step is to take an exposure.
If the exposure opening is not formed in the instant film pack at a size of appearance of a large area of the photosensitive side, the light shielding cover is naturally unnecessary. If the light shielding cover is omitted, the thrust preventing flap and the light shielding sheet which would be on the light shielding sheet must be attached to the case. The light shielding sheet and the thrust preventing flap according to the prior art are removed together with the light shielding cover. However, the attachment of the light shielding sheet and the thrust preventing flap on the case results in their remaining state with the thrust preventing flap. It is likely the operation of the advancing claw mechanism and ejection of the instant photo film are seriously influenced by the light shielding sheet and the thrust preventing flap.